Assessment of quantitative structure-activity relationship of toxicity prediction models for Korean chemical substance control legislation

OBJECTIVES: For successful adoption of legislation controlling registration and assessment of chemical substances, it is important to obtain sufficient toxicological experimental evidence and other related information. It is also essential to obtain a sufficient number of predicted risk and toxicity results. Particularly, methods used in predicting toxicities of chemical substances during acquisition of required data, ultimately become an economic method for future dealings with new substances. Although the need for such methods is gradually increasing, the-required information about reliability and applicability range has not been systematically provided. METHODS: There are various representative environmental and human toxicity models based on quantitative structure-activity relationships (QSAR). Here, we secured the 10 representative QSAR-based prediction models and its information that can make predictions about substances that are expected to be regulated. We used models that predict and confirm usability of the information expected to be collected and submitted according to the legislation. After collecting and evaluating each predictive model and relevant data, we prepared methods quantifying the scientific validity and reliability, which are essential conditions for using predictive models. RESULTS: We calculated predicted values for the models. Furthermore, we deduced and compared adequacies of the models using the Alternative non-testing method assessed for Registration, Evaluation, Authorization, and Restriction of Chemicals Substances scoring system, and deduced the applicability domains for each model. Additionally, we calculated and compared inclusion rates of substances expected to be regulated, to confirm the applicability. CONCLUSIONS: We evaluated and compared the data, adequacy, and applicability of our selected QSAR-based toxicity prediction models, and included them in a database. Based on this data, we aimed to construct a system that can be used with predicted toxicity results. Furthermore, by presenting the suitability of individual predicted results, we aimed to provide a foundation that could be used in actual assessments and regulations.

Radiological Measurements of Cervical Spinal Canal in Normal Korean Adults

The concept of using radiographic measurements in the diagnosis of intraspinal lesions is not new. There have been many studies for the measurements of the spinal canal and normal ranges of variation in normal human and patient with spondylosis or developments stenosis. The author measured the cervical spinal canal in 89 normal Korean adults plain X-rays(male;62 cases, female;27 cases) in order to establish a range of normal value in X-ray diagnosis. The sagittal diameters of the cervical spinal canal were measured from the middle of the posterior surface of the vertebral body to the "nearest point" on the cortical line at the point of fusion of the corresponding laminae. The transverse diameters of the cervical spinal canal were measured the interpediculate distance which represents the greatest diameter of the cervical neural canal from C3 to C7. According to the normal ranges of the sagittal and transverse diameters of the cervical spinal canal, It was concluded: 1. The sagittal diameter is progressively narrowed from C1 to C4(Mean+/-SD=C1; 21.83+/-2.43, C2; 19.30+/-2.39, C3; 17.14+/-2.65, C4; 16.41+/-2.47) thereafter it is progressively widened from C5 to C7(C5; 16.79+/-2.72, C6; 17.39+/-2.74, C7; 17.68+/-2.81). 2. The transverse diameter is progressively widened from C3 to C6(Mean+/-SD= C3; 27.10+/-2.23, C4; 28.05+/-2.30, C5; 28.95+/-2.36, C6; 29.12+/-2.25) thereafter it is narrowed in C7(C7; 27.81+/-2.28). 3. Generally, the length of the male are more longer than that of female both in sagittal and transverse diameter in cervical spinal canal(average;1.29 mm). 4. Ranges of normal values both in sagittal and transverse diameters in whole length of the cervical spinal canal were established(Fig. 5. Table 4, and 5).